Plate/screw locking mechanism devices, systems and methods

ABSTRACT

The present disclosure relates, in some embodiments, to locking mechanisms for a fastener (e.g., a bone screw) and associated devices, systems, and methods. According to some embodiments, a lockable bone plate assembly may comprise, for example, a bone plate and a bone screw assembly. A bone plate may comprise, in some embodiments, at least one through hole, the at least one through hole having at least one bone plate hole circumferential recess. According to some embodiments, a bone screw assembly may comprise (a) a bone screw, (b) at least one deployable protrusion, and/or (c) a protrusion driver. The present disclosure further relates, in some embodiments, to methods for bone (e.g., vertebral) fixation. For example, a method may comprise contacting at least a portion of a spine (e.g., cervical spine) of a subject with a lockable bone plate assembly.

FIELD OF THE DISCLOSURE

The present disclosure relates, in some embodiments, to lockingmechanisms for a fastener (e.g., a bone screw) and associated devices,systems, and methods.

BACKGROUND OF THE DISCLOSURE

The spinal column is a highly complex anatomical structure capable ofbearing substantial loads while displaying remarkable flexibility. Avariety of conditions (e.g., traumatic, pathological, developmental,and/or degenerative) exist that may impair the load bearing capacity,flexibility, or both of a subject's spine. Under such circumstances andothers, it may be desirable to attach one or more appliances to asubject's spine using one or more fasteners (e.g., screws, clamps,clips, and/or other devices). A fastener (e.g., a screw) inserted intothe spine may backout of the insertion site, for example, through thecourse of a subject's normal activities.

SUMMARY

Accordingly, a need has arisen for improved methods and mechanisms forsecuring a fastener (e.g., a bone screw). The present disclosurerelates, in some embodiments, to locking mechanisms for a fastener(e.g., a bone screw) and associated devices, systems, and methods.According to some embodiments, a locking mechanism may reduce, arrest,and/or prevent backout of a fastener.

The present disclosure relates, in some embodiments, to a lockable boneplate assembly, which may comprise, for example, a bone plate and a bonescrew assembly. A bone plate may comprise, in some embodiments, at leastone through hole, the at least one through hole having at least one boneplate hole circumferential recess. According to some embodiments, a bonescrew assembly may comprise (a) a bone screw, (b) at least onedeployable protrusion, and/or (c) a protrusion driver. A deployableprotrusion may have a stowed position (e.g., substantially within thebone screw) and/or a deployed position (e.g., at least partiallyprotruding from the bone screw). In a deployed position, a deployableprotrusion may engage a bone plate hole circumferential recess.According to some embodiments, a protrusion driver may be in mechanicalcommunication with a deployable protrusion and operable to drive thedeployable protrusion from a stowed position to a deployed position. Avertical position of a bone screw relative to a bone and/or a bone screwplate may be locked, in some embodiments, when a deployable protrusionis in a deployed position.

According to some embodiments, a protrusion driver may be configured tomove a deployable protrusion radially outwardly from a stowed positionto a deployed position. A protrusion driver and/or a deployableprotrusion may have a stowed position and/or a deployed position. Forexample, a protrusion driver may have a deployed position correspondingto a deployed position of a deployable protrusion. A protrusion drivermay be configured to be locked in a deployed position in someembodiments. For example, a bone screw may comprise a first surfacefeature (e.g., ridge, bump, nub, point, groove, slot, and/or the like)and a protrusion driver may comprise a second surface feature (e.g.,ridge, bump, nub, point, groove, slot, and/or the like) configured toengage the first surface feature and lock the protrusion driver in itsdeployed position. According to some embodiments, a bone screw maycomprise a central, longitudinal axis, a bone screw body, and/or a bonescrew head. A bone screw head may, for example, comprise at least onenotch (e.g., a centrally-located and/or top-facing notch). One or more(e.g., up to all) bone screw head notches may comprise a torque surfaceconfigured to receive a torque and translate the torque to rotation ofthe bone screw about the central, longitudinal axis (e.g., clockwise orcounterclockwise). A bone screw body may comprise one or more threadsthat taper to a tip (e.g., the lengthwise end opposite a bone screwhead). For example, a lockable bone plate assembly may comprise a bonescrew having a central longitudinal axis and comprising a bone screwbody comprising threads that taper to a tip and a bone screw head fixedto the bone screw body on the end opposite the tip, the bone screw headcomprising at least one notch. According to some embodiments, a bonescrew head may comprise a groove, for example, an annular groove. Anannular groove may be positioned in a bone screw head also comprising anotch in some embodiments. For example, an annular groove may encircle anotch (e.g., a centrally-located and/or top-facing notch).

A bone screw assembly (e.g., comprised in a lockable bone plateassembly) may comprise an annular bone screw cam and/or an annular bonescrew cap according to some embodiments. An annular bone screw cam maybe positioned, for example, in an annular groove of a bone screw head.In some embodiments, an annular bone screw cam may comprise on its outercircumferential surface at least one axial groove, at least one axialdeep recess, at least one axial shallow recess between the axial grooveand the axial deep recess, and/or at least one cam surface. An annularbone screw cap may comprise, according to some embodiments, a firstsurface comprising at least one bone screw cap notch and second surfaceopposing the first facing the annular bone screw cam and comprising atleast one prong. In some embodiments, a deep recess may be configured toengage a deployable protrusion in its stowed position a shallow recessmay be configured to engage the deployable protrusion in its deployedposition, and/or a axial groove may be in mechanical communication witha prong to produce tandem rotation of an annular bone screw cam and anannular bone screw cap about the central, longitudinal axis of the bonescrew. An annular bone screw cap may comprise, according to someembodiments, at least one circumferential notch comprising a torquesurface, the torque surface configured to receive a torque and translatethe torque to rotation of the bone screw cap about the central,longitudinal axis.

A bone screw head may comprise a central cavity in some embodiments. Acentral cavity may comprise, for example, a central cavity innersurface, the inner surface comprising a stowed circumferential recess(e.g., defining a plane perpendicular to the central, longitudinal axisof the bone screw) and a deployed circumferential recess (e.g., defininga plane perpendicular to the central, longitudinal axis of the bonescrew), wherein the deployed circumferential recess is closer to the tipthan the stowed circumferential recess.

In some embodiments, a bone screw assembly may comprise an annular bonescrew race in the central cavity having a stowed position and a deployedposition, the annular bone screw race comprising a first end, an outercircumferential surface comprising at least one circumferential nub(e.g., defining a plane perpendicular to the central, longitudinal axisof the bone screw) and at least one cam surface, and a second endopposite the first end, wherein the nub engages the stowedcircumferential recess in the stowed position of the race and the nubengages the deployed circumferential recess in the deployed position ofthe race. A deployable protrusion may comprise a bone screw pin having agenerally cylindrical shape and comprising a proximal end in mechanicalcommunication with the at least one cam surface of the annular bonescrew race and a distal end engage able with the at least one bone platehole circumferential recess. An annular bone screw race, in someembodiments, may comprise a slot spanning its radial and longitudinalthickness). According to some embodiments, an annular bone screw racemay comprise a central aperture comprising a central aperture surface,the central aperture surface comprising threads. An cam, in someembodiments, may comprise a first end having at least one cam notch. Acam slot may be distinct from or contiguous with at least one cam notchin some embodiments.

The present disclosure relates, in some embodiments, to methods for bone(e.g., vertebral) fixation. For example, a method may comprisecontacting at least a portion of a spine (e.g., cervical spine) of asubject with a lockable bone plate assembly. A method, according to someembodiments, may comprise contacting at least one bone screw assembly ofa lockable bone plate assembly with a bone of a subject, turning the atleast one bone screw assembly (e.g., applying a torque to a torquesurface) until it is secured in the bone (e.g., with threads at leastpartially embedded in the bone). In some embodiments, a method maycomprise moving a deployable protrusion (e.g., from a stowed position)into a deployed position. A fixation method using a lockable back plateassembly having four bone screw assemblies may comprise, according tosome embodiments, (a) contacting a first bone site with the first bonescrew assembly; (b) turning the first bone screw assembly until it issecured in the first bone site; (c) moving a deployable protrusion inthe first bone screw assembly into a deployed position, and/or (d)repeating (a), (b), and/or (c) for a second bone screw assembly and asecond bone screw site, a third bone screw assembly and a third bonescrew site, and/or a fourth bone screw assembly and a fourth bone screwsite. Moving a deployable protrusion into a deployed position maycomprise, in some embodiments, turning (e.g., applying a torque to atorque surface) a bone screw cap engaged with a bone screw cam such thatthe bone screw cam cams a deployable protrusion into a deployedposition. Moving a deployable protrusion into a deployed position maycomprise, in some embodiments, pressing a bone screw cam comprising acircumferential camming surface downwardly (e.g., toward the tip of thebone screw assembly) such that the circumferential camming surface camsa deployable protrusion (e.g., radially outwardly from a central,longitudinal axis of a bone screw) into a deployed position. In someembodiments, a method may comprise moving a deployable protrusion into adeployed position in which it engages at least a portion of a bone screwplate (e.g., a slot, recess, ridge, groove, indentation, and/or thelike). For example, a method may comprise engaging a deployableprotrusion in at least a portion of a bone screw plate in a way thatlimits, reduces, and/or prevents vertical movement (e.g., backout) of abone screw assembly. A method may comprise, according to someembodiments, locking a deployable protrusion into a deployed position.

The present disclosure relates, in some embodiments, to a method ofremoving a lockable bone plate assembly comprising a bone screw assemblyengaged in a bone, wherein the bone screw assembly comprises adeployable protrusion in a deployed position, the method comprisingmoving the deployable protrusion from the deployed position to a stowedposition. For example, a method may comprise moving a deployableprotrusion into a stowed position. According to some embodiments, movinga deployable protrusion into a stowed position may comprise turning(e.g., applying a torque to a torque surface) a bone screw cap engagedwith a bone screw cam such that the bone screw cam disengages from thedeployable protrusion, thereby freeing it to slide to a stowed position,for example, under the influence of radially, inwardly directed tension.Moving a deployable protrusion into a stowed position may comprise, insome embodiments, pulling a bone screw cam comprising a circumferentialcamming surface upwardly (e.g., away from the tip of the bone screwassembly) such that the bone screw cam disengages from the deployableprotrusion, thereby freeing it to slide to a stowed position, forexample, under the influence of radially, inwardly directed tension.Tension may arise, in some embodiments, from backout pressure exerted bythe arrangement of a lockable back brace assembly relative to a bone,from turning the bone screw assembly to back it out of a bone plateand/or bone such that the distal tip of the deployable protrusioncontacts (e.g., cams against) an inner surface of a bone plate throughhole, and/or through compression forces exerted by a deployableprotrusion notch sized to contact (e.g., squeeze) the deployableprotrusion while in a deployed position.

BRIEF DESCRIPTION OF THE DRAWINGS

Some embodiments of the disclosure may be understood by referring, inpart, to the present disclosure and the accompanying drawings, wherein:

FIG. 1 illustrates a perspective view of a bone plate assembly accordingto a specific example embodiment of the disclosure;

FIG. 2A illustrates an exploded view of a bone screw assembly accordingto a specific example embodiment of the disclosure;

FIG. 2B illustrates a perspective view of a bone screw according to aspecific example embodiment of the disclosure;

FIG. 2C illustrates a perspective view of a bone screw cam according toa specific example embodiment of the disclosure;

FIG. 2D illustrates a perspective view of a bone screw cap according toa specific example embodiment of the disclosure;

FIG. 3A illustrates a perspective view of a bone screw assembly in anundeployed position according to a specific example embodiment of thedisclosure;

FIG. 3B illustrates a perspective view of a bone screw assembly in adeployed position according to a specific example embodiment of thedisclosure;

FIG. 3C illustrates a plan view of a bone screw assembly in anundeployed position according to a specific example embodiment of thedisclosure;

FIG. 3D illustrates a plan view of a bone screw assembly in a deployedposition according to a specific example embodiment of the disclosure;

FIG. 3E illustrates a section view of a bone screw assembly in anundeployed position according to a specific example embodiment of thedisclosure;

FIG. 3F illustrates a section view of a bone screw assembly in adeployed position according to a specific example embodiment of thedisclosure;

FIG. 4 illustrates a perspective view of a bone plate assembly accordingto a specific example embodiment of the disclosure;

FIG. 5A illustrates an exploded view of a bone screw assembly accordingto a specific example embodiment of the disclosure;

FIG. 5B illustrates a perspective view of a bone screw according to aspecific example embodiment of the disclosure;

FIG. 5C illustrates a perspective view of a bone screw cam according toa specific example embodiment of the disclosure;

FIG. 5D illustrates a perspective view of a bone screw cap according toa specific example embodiment of the disclosure;

FIG. 6A illustrates a perspective view of a bone screw assembly in anundeployed position according to a specific example embodiment of thedisclosure;

FIG. 6B illustrates a perspective view of a bone screw assembly in adeployed position according to a specific example embodiment of thedisclosure;

FIG. 6C illustrates a plan view of a bone screw assembly in anundeployed position according to a specific example embodiment of thedisclosure;

FIG. 6D illustrates a plan view of a bone screw assembly in a deployedposition according to a specific example embodiment of the disclosure;

FIG. 6E illustrates a section view of a bone screw assembly in anundeployed position according to a specific example embodiment of thedisclosure;

FIG. 6F illustrates a section view of a bone screw assembly in adeployed position according to a specific example embodiment of thedisclosure;

FIG. 7 illustrates a perspective view of a bone plate assembly accordingto a specific example embodiment of the disclosure;

FIG. 8A illustrates an exploded view of a bone screw assembly accordingto a specific example embodiment of the disclosure;

FIG. 8B illustrates a perspective view of a bone screw according to aspecific example embodiment of the disclosure;

FIG. 8C illustrates a perspective view of a bone screw cam according toa specific example embodiment of the disclosure;

FIG. 8D illustrates a perspective view of a bone screw cap according toa specific example embodiment of the disclosure;

FIG. 9A illustrates a perspective view of a bone screw assembly in anundeployed position according to a specific example embodiment of thedisclosure;

FIG. 9B illustrates a perspective view of a bone screw assembly in adeployed position according to a specific example embodiment of thedisclosure;

FIG. 9C illustrates a plan view of a bone screw assembly in anundeployed position according to a specific example embodiment of thedisclosure;

FIG. 9D illustrates a plan view of a bone screw assembly in a deployedposition according to a specific example embodiment of the disclosure;

FIG. 9E illustrates a section view of a bone screw assembly in anundeployed position according to a specific example embodiment of thedisclosure;

FIG. 9F illustrates a section view of a bone screw assembly in adeployed position according to a specific example embodiment of thedisclosure;

FIG. 10A illustrates a perspective view of a bone plate assemblyaccording to a specific example embodiment of the disclosure;

FIG. 10B illustrates a perspective view of a bone plate according to aspecific example embodiment of the disclosure;

FIG. 10C illustrates a perspective view of a bone plate according to aspecific example embodiment of the disclosure;

FIG. 11A illustrates an exploded view of a bone screw assembly accordingto a specific example embodiment of the disclosure;

FIG. 11B illustrates a perspective view of a bone screw according to aspecific example embodiment of the disclosure; and

FIG. 11C illustrates a perspective view of a bone screw cam according toa specific example embodiment of the disclosure.

FIG. 12A illustrates a perspective view of a bone screw assembly in anundeployed position according to a specific example embodiment of thedisclosure;

FIG. 12B illustrates a perspective view of a bone screw assembly in adeployed position according to a specific example embodiment of thedisclosure;

FIG. 12C illustrates a plan view of a bone screw assembly in anundeployed position according to a specific example embodiment of thedisclosure;

FIG. 12D illustrates a plan view of a bone screw assembly in a deployedposition according to a specific example embodiment of the disclosure;

FIG. 12E illustrates a section view of a bone screw assembly in anundeployed position according to a specific example embodiment of thedisclosure;

FIG. 12F illustrates a section view of a bone screw assembly in adeployed position according to a specific example embodiment of thedisclosure;

Table 1 below includes the reference numerals used in this disclosure inconnection with specific example embodiments.

TABLE 1 Reference Numerals Bone Plate Assembly 100 200 300 400 BonePlate 110 210 310 410 Body 111 211 311 411 Through Hole 112 212 312 412Through Hole Recess 113 213 313 413 Through Hole Inner Surface 114 214314 414 Through Hole Ridge 115 215 315 415 Mount 116 216 316 416Aperture 117 217 317 417 Bone Screw Assembly 120 220 320 420 Bone Screw130 230 330 430 Bone Screw Body 131 231 331 431 Threads 132 232 332 432Threaded Portion 133 233 333 433 Bone Screw Tip 134 234 334 434 CentralAxis 135 235 335 435 Bone Screw Head 140 240 340 440 Body 141 241 341441 Notch 142 242 342 442 Torque Surface 143 243 343 443 Recess 144 244344 444 Hole 145 245 345 445 Annular Groove 146 246 346 446 StowedCircumferential Recess 147 247 347 447 Deployed Circumferential Recess148 248 348 448 Stop 149 249 349 449 Bone Screw Cam 150 Body 151 Groove152 Deep Recess 153 Shallow Recess 154 Central Aperture 155 CentralAperture Inner Surface 156 Bone Screw Race 260 360 460 Body 261 361 461Notch 262 362 462 Notch Surface 263 363 463 Cam Surface 264 364 464Central Aperture 265 365 465 Central Aperture Inner Surface 266 366 466Slot 267 367 467 Nub 268 368 468 Threads 369 Bone Screw Cap 170 Body 171Notch 172 Torque Surface 173 Prong 174 Central Aperture 175 CentralAperture Inner Surface 176 Bone Screw Ball Bearing 180 Bone Screw Pin285 385 485 Proximal End 286 386 486 Ridge 287 387 487 Distal End 288388 488

DETAILED DESCRIPTION

The present disclosure relates, in some embodiments, to lockingmechanisms for a fastener (e.g., a bone screw) and associated devices,systems, and methods. For example, a device with a screw lockingmechanism may comprise a bone plate assembly. A bone plate assembly maybe easy to use in some embodiments. A bone plate assembly, according tosome embodiments, may include a reversible locking mechanism. In someembodiments, a bone screw assembly may include a locking mechanism thatdoes not rely solely on friction. A bone plate assembly may be secured,according to some embodiments, to a cervical plate (e.g., an anteriorcervical plate).

Bone Plate Assembly

A bone plate assembly may permit at least partial load sharing betweenbones or bone sections that it connects. For example, a bone plate maypermit at least partial sharing weight of vertebral bodies across a bonegraft site. It may be desirable, in some embodiments, to permit somemovement and/or weight to be borne by bone (e.g., to facilitatehealing). According to some embodiments, a bone plate assembly may bestrong enough to resist collapsing forces and/or abnormal angulationduring the healing of a bone. It may be desirable, in some embodiments,for a bone plate assembly to be secure in its attachment to the spine(e.g., to resist and/or prevent migration of the implant or back out ofthe screws from the bone which could result in damage to the structuressurrounding the spine, causing severe and potentially life threateningcomplications).

A bone plate assembly may comprise a bone screw assembly and a boneplate according to some embodiments. Optionally, a bone plate assemblymay comprise, in some embodiments, a screw retaining member configuredto cover at least a portion of one or more bone screws. For example, ascrew retaining member may be provided with an aperture that receives afastener (e.g., a screw) that fixes the screw retaining member to a boneplate. According to some embodiments, a bone plate assembly may befastened to one or more bones. For example, a bone plate assembly may befastened to a single bone (e.g., across a fracture or break) or to twoor more bones (e.g., vertebrae). A bone plate may comprise one or moreapertures (e.g., from 1 to about 10 apertures). Each aperture mayreceive a bone screw, which may be fitted into a drill hole, forexample, to fasten the bone plate to bone.

Each member of a bone plate assembly independently may comprise one ormore materials suitable for implantation in a subject (e.g., a humanand/or a non-human animal). Each member of a bone plate assemblyindependently may comprise one or more materials capable of providingsuitable structural and/or mechanical strength and/or integrity.Examples of suitable materials may include, without limitation,titanium, cobalt chromium, stainless steel, alloys thereof, and/orcombinations thereof. Examples of suitable materials may include,without limitation, plastics, fibers (e.g., carbon fiber) and/orbioabsorbable materials. Each member of a bone plate assemblyindependently may comprise one or more one or more surface coatings(e.g., for drug delivery, to promote healing, to aid installation, toresist infection, to increase and/or reduce friction between components,and the like).

Bone Screw Assembly

A bone screw assembly may comprise, in some embodiments, a bone screwhaving a central, longitudinal axis, a deployable protrusion having astowed position (e.g., substantially recessed within the bone screw) anda deployed position (e.g., at least a portion protrudes from the bonescrew), and a protrusion driver in mechanical communication with thedeployable protrusion. According to some embodiments, a protrusiondriver may be in direct and/or indirect contact with a deployableprotrusion. In some embodiments, a protrusion driver may be configuredto displace a deployable protrusion from a stowed position to a deployedposition. For example, a protrusion driver may displace a deployableprotrusion radially outwardly, away from the central, longitudinal axisof a bone screw.

Bone Screw

According to some embodiments a bone screw may have a centrallongitudinal axis and comprise a bone screw body and a bone screw head.A bone screw body may be configured to be secured to a matrix (e.g.,bone). For example, a bone screw body may comprise threads along atleast a portion of its length.

A head may or may not have the same geometry and/or radius as a threadedportion. For example, it may have a shape other than round and/or mayhave a larger or smaller radius as compared to, for example, the averageradius of a threaded portion, the minimum radius (e.g., sampled at ornear the midpoint of a bone screw body longitudinal axis), the maximumradius, or any other radial metric of the threaded portion. A head maycomprise, in some embodiments, one or more surfaces configured toreceive a corresponding tool to fit (e.g., drive) a screw into position(e.g., screwed into and secured to a matrix). These one or more surfacesmay be positioned anywhere on a head including, for example, near thecenter of a head and/or on a head's circumference.

According to some embodiments, a bone screw head may comprise at leastone recess sized to house a deployable protrusion. For example, a recessmay comprise a through hole (a) positioned approximately perpendicularto the center, longitudinal axis of a bone screw and/or (b) spaced awayfrom the center, longitudinal axis of a bone screw. In some embodiments,a deployable protrusion may be positioned such that a portion of theprotrusion is more proximal to the center, longitudinal axis of a bonescrew and a portion of the protrusion is more distal to the center,longitudinal axis of a bone screw. For example, a stowed deployableprotrusion may partially or completely occupy a through hole such thatlittle or none of its distal portion protrudes from a bone screw head.In some embodiments, a proximal end of a deployable protrusion may be inmechanical communication (e.g., direct and/or indirect) with aprotrusion driver. A protrusion driver may displace a deployableprotrusion to a deployed position, for example, by exerting a force(e.g., a force directed radially outwardly) on the deployableprotrusion's proximal end.

Deployable Protrusion

A deployable protrusion may have any desired size and/or shape. Forexample, it may be configured, in some embodiments, in any regular orirregular geometric shape including, without limitation, a sphere, acylinder, a box, a torus, a cone, a prism, a disk, and/or combinationsthereof. For example, a deployable protrusion may comprise a generallypin shape and/or a generally ball bearing shape. The size of adeployable protrusion may be scaled in proportion to the other partswith which it fits and/or in proportion to the bones to which a devicecontaining the protrusion is to be affixed. A deployable protrusion maycomprise any desired material. For example, a deployable protrusion maycomprise a rigid or semi-rigid material capable of withstandingapplication of a shear force between a bone screw and a bone plate. Adeployable protrusion may have one or more features including ridges,recesses, surface coatings, and/or combinations thereof according tosome embodiments. For example, a deployable protrusion may have afeature (e.g., a circumferential ridge) configured to engage (e.g.,contact) a stop in a bone screw head to hold it in a stowed positionand/or a deployed position. A deployable protrusion may have a feature(e.g., a circumferential ridge) configured to engage (e.g., contact) astop in a bone screw head to resist or prevent the protrusion formreceding too far into a bone screw head or extending too far out of abone screw head.

Protrusion Driver

According to some embodiments, a protrusion driver may have any desiredsize and/or shape. For example, it may be configured, in someembodiments, in any regular or irregular geometric shape including,without limitation, a sphere, a cylinder, a box, a torus, a cone, aprism, a disk, and/or combinations thereof. For example, a protrusiondriver may comprise a generally torus shape. The size of a protrusiondriver may be scaled in proportion to the other parts with which it fitsand/or in proportion to the bones to which a device containing theprotrusion is to be affixed. A protrusion driver may comprise anydesired material. For example, a protrusion driver may comprise a rigidor semi-rigid material capable of supporting application of a force to adeployable protrusion (e.g., a force sufficient to displace thedeployable protrusion into a deployed position and/or hold thedeployable protrusion in a deployed position).

A protrusion driver may be configured, according to some embodiments, asa bone screw race. For example, a bone screw race may be configured tomove (e.g., reversibly or irreversibly) parallel to the central,longitudinal axis of a bone screw and, in so doing, displace adeployable protrusion into a deployed position. In some embodiments, aprotrusion driver may be configured as a bone screw cam. For example, abone screw cam may be configured to rotate (e.g., reversibly orirreversibly) about the central, longitudinal axis of a bone screw and,in so doing, displace a deployable protrusion into a deployed position.

Bone Plate

According to some embodiments, a bone plate may be any object configuredto receive two or more bone screw assemblies. A bone plate may comprise,in some embodiments, a rigid and/or semi-rigid body with at least twothrough holes, each configured to receive a bone screw assembly. Athrough hole may have a generally cylindrical shape and/or comprise oneor more recesses and/or one or more protrusions. Each recess may beconfigured to engage a ball bearing, pin, or other protrusion from abone screw assembly (e.g., from a bone screw assembly head). Forexample, each recess present may be positioned along the circumference(e.g., in a regular or irregular pattern if there is more than onerecess) of a through hole.

Methods of Use

A bone screw assembly may be installed in a matrix (e.g., bone), in someembodiments, by drilling a hole in a bone, tapping the hole, andthreading the bone screw assembly into the bone. According to someembodiments, drilling a hole may comprise holding a guide next to and/orattaching a guide to a bone and/or bone plate. For example, a drill maybe inserted into a guide, a hole drilled into a bone, and the drill andguide removed. Care may be taken to ensure that a tap and/or a bonescrew are inserted at substantially the same angle as the drill hole.

A method of installing a bone screw assembly comprising a bone screw, adeployable protrusion, and a protrusion driver may comprise, in someembodiments, inserting the bone screw assembly into a bone (e.g., in apre-drilled hole in a bone) and manipulating the protrusion driver todeploy the deployable protrusion from a stowed position to a deployedposition.

Methods of Therapy

The present disclosure relates, according to some embodiments, to amethod of bone fixation (e.g., spinal fixation) may comprise. Forexample, a method may comprise installing a bone plate assembly having alocking mechanism (e.g., an anti-backout mechanism for component bonescrews) in a subject. A method may comprise, in some embodiments,drilling a hole, tapping the hole, and threading a bone screw into abone. A method may comprise installing a self-drilling screw withoutpre-drilling and/or without tapping according to some embodiments. Aguide may be held next to or attached to a plate in some embodiments. Adrill may be inserted, according to some embodiments, into the guide andthe hole drilled into the bone. A guide, if used, may be removed and atap may be threaded through the hole (e.g., following the same orsubstantially the same angle as a drill hole. It may be desirable toproceed with caution, for example, to prevent the sharp edges of the tapfrom damaging surrounding tissues or in creating too large a tap hole bytoggling the handle of the tap. This damage may reduce the security ofthe screw bite into the bone and/or increase the likelihood of screwpullout. After tapping, a screw may be guided at a proper angle into ahole that has been created. In some embodiments, inadvertentmisalignment may reduce pullout strength and/or may result in damage tosurrounding nerves or arteries.

In some embodiments, a method may comprise contacting a bone plateassembly comprising at least one fastener with a bone of subject,inserting the fastener in the bone, locking the fastener, andcombinations thereof. For example, inserting and locking, optionally maybe repeated for up to all of the fasteners in the bone plate assembly.Locking a fastener comprising at least one protrusion and at least oneprotrusion driver in mechanical communication with the at least oneprotrusion may comprise moving (e.g., rotating and/or sliding) theprotrusion driver such that is moves the at least one or moreprotrusions into at least partial engagement with a bone plate (e.g., abone plate detent, bone plate groove, bone plate recess, bone plateslot, bone plate well, bone plate hole, bone plate channel, and/or thelike).

A method of bone fixation may be used to address (e.g., prevent, treat,ameliorate, ease, and/or relieve) one or more conditions and/or symptomsthereof. Conditions that may be addressed include, according to someembodiments, traumatic conditions, pathological conditions,developmental conditions, degenerative conditions, and/or combinationsthereof. For example, a method of bone fixation may be used to addressdegenerative disc disease, spondylolisthesis, a bone fracture or break,spinal stenosis, deformities (e.g., scoliosis, kyphosis and/orlordosis), tumor, pseudoartrosis, necrosis, a bulging or herniated disc,and combinations thereof. In some embodiments, a method of bone fixationmay be applied to any bone(s) in a subject body. A method may beapplied, for example, to a subject's cervical spine (e.g., C2-C7). Ahealthcare professional exercising reasonable prudence and care maydetermine which embodiment is most desirable for a particular subject.

Specific Example Embodiments

FIG. 1 illustrates a perspective view of bone plate assembly 1100according to a specific example embodiment of the disclosure. As shownbone plate assembly 1100 comprises bone plate 1110 and bone screwassembly 1120. Bone plate 1110 comprises body 1111, through holes 1112,mount 1116, and aperture 1117. Each through hole 1112 defines a central,longitudinal axis generally perpendicular to the plane of body 1111(e.g., and/or ±˜5° and/or ±˜20°). Each through hole 1112 comprises innersurface 1114 having recess 1113 and ridge 1115. Recess 1113 may extendalong the entire circumference of inner surface 1114 and/or lie in aplane generally perpendicular to the central, longitudinal axis ofthrough hole 1112. Bone screw assembly 1120 comprises bone screw 1130,threads 1132, cam 1150, cap 1170, and ball bearings 1180. Bone screwassembly 1120 is fitted into one of through holes 1112 with each ballbearing 1180 in a deployed position, engaged in through hole recess1113. According to some embodiments, one or more of recesses 1113 may besized the same as or just slightly larger than the size of ball bearing1180. Bone plate assembly 1100 may comprise, in some embodiments, a likenumber of bone screw assemblies 1120 and through holes 1112.

A bone screw assembly 2120 may comprise bone screw 2130, deployableprotrusion 2180, protrusion driver 2150, and, optionally, cap 2170,according to some embodiments (e.g., FIGS. 2A-2D). Bone screw 2130 maycomprise body 2131 and bone screw head 2140. Bone screw body 2131 mayhave one or more threads 2132 spanning threaded portion 2133, which maybe configured to advance and/or fix bone screw 2130 in a hole in amatrix (e.g., bone). For example, threads 2132 may spirally surround theouter longitudinal circumference of body 2131, tapering to tip 2134.Bone screw body 2130 may have central, longitudinal axis 2135.

Bone screw head 2140 may comprise notch 2142, torque surface 2143,through holes 2144, through holes 2145, and annular groove 2146. Notch2142 may be configured to rotate about an axis parallel to and/or rotatein a plane generally perpendicular to longitudinal axis 2135 of bonescrew 2130. Notch 2142 may be configured to receive a mated installationtool (e.g., a screwdriver, a torx, an Allen key (e.g., 4-, 5-, or6-sided)). Upon application of a force (e.g., torque) to torque surface2143, bone screw 2130 may rotate about its central longitudinal axis2135 and, optionally, propel tip 2134 into a matrix (e.g., bone).Annular groove 2146 may surround notch 2142. Annular groove 2146 may liein a plane generally perpendicular to longitudinal axis 2135 of bonescrew 2130 and/or generally parallel to the rotational plane of notch2142. Holes 2144 may receive ball bearings 2180. Each hole 2144 and/oreach hole 2145 may independently have a longitudinal axis that isperpendicular to center, longitudinal axis 2135 of bone screw 2130. Eachhole 2144 may independently have a diameter that is uniform along itsfull length. In some embodiments, each hole 2144 may independently havea narrowing at or near the end more distal to center, longitudinal axis2135 of bone screw 2130. Holes 2144 and 2145 may be distributed atregular intervals, as shown, or irregular intervals around thecircumference of bone screw head 2140. Bone screw 2130 may be a singlepiece or two or more conjoined parts according to some embodiments.

Bone screw cam 2150 may fit (e.g., rotatably fit) within annular groove2146. For example, cam 2150 may fit within annular groove 2146 such thatit may rotate about and/or rotate in a plane generally perpendicular tolongitudinal axis 2135 of bone screw 2130. Cam 2150 may rotate clockwiseand/or counterclockwise in some embodiments. Cam 2150 may be generallycircular (e.g., annular) with a diameter greater (e.g., much greater)than it's thickness. Cam 2150 may comprise body 2151, which may itselfdefine and/or comprise central aperture 2155. Central aperture 2155 maysurround notch 2142. Cam 2150 may comprise grooves 2152, deep recesses2153, and/or shallow recesses 2154, for example, along its outer edge.Each recess 2153 and/or each recess 2154 may independently contact oneor more ball bearings 2180.

Bone screw cap 2170 may fit (e.g., rotatably fit) within annular groove2146. For example, cap 2170 may fit within annular groove 2146 such thatit may rotate about and/or rotate in a plane generally perpendicular tolongitudinal axis 2135 of bone screw 2130. Cap 2170 may rotate clockwiseand/or counterclockwise in some embodiments. Cap 2170 may be generallycircular (e.g., annular) with a diameter greater (e.g., much greater)than it's thickness. Cap 2170 may comprise body 2171, which may itselfdefine and/or comprise central aperture 2175. Central aperture 2175 maysurround notch 2142. Cap 2170 may comprise notch 2172, torque surface2173, and prong 2174. Each notch 2172 may span the radial thickness ofbody 2171. Two or more notches 2172 may be positioned on the same faceof cap 2170 as one another. Two or more prongs 2174 may be positioned onthe same face of cap 2170 as one another. One or more notches 2172 maybe positioned on the opposite face of cap 2170 as one or more prongs2174. Each prong 2174 may independently contact (e.g., fit within) agroove 2152 on bone screw 2130. Cap may engage cam 2150 (e.g., throughcontact between grooves 2152 and prongs 2174) such that a force (e.g.,torque) applied to notch 2174 (e.g., via torque surface 2173) may rotatenot only cap 2170, but also cam 2150. Cap 2170 may comprise one or morefeatures (e.g., welds, swags, and/or others) that secure it to bonescrew 2130, for example, to retain itself, cam 2150, and/or bearings2180 in desirable and/or functional relation to bone screw 2130.

FIGS. 3A-3F illustrate perspective, plan, and section views of bonescrew assembly 3120 with ball bearings in a stowed position (FIGS. 3A,3C, and 3E) and a deployed position (FIGS. 3B, 3D, and 3F). As shown,each ball bearing 3180 in an undeployed position may (a) occupy a hole3144, (b) engage a deep recess 2153 such that its outer edge issubstantially flush with the outer surface of head 3140, and/or (c) havelittle or no opportunity for contact with plate 2110 (FIGS. 3A, 3C, and3E). Each ball bearing 3180 in a deployed position may (a) partiallyoccupy a hole 3144, (b) engage a shallow recess 3154 such that itprotrudes from hole 3144 beyond the outer surface of head 3140, and/or(c) has sufficient exposure to contact plate 3110 (FIGS. 3B, 3D, and3F).

In use, each ball bearing 3180 may be deployed upon rotation (e.g.,clockwise or counterclockwise) of cam 3150 from a position that permitsengagement of each ball bearing 3180 with a deep recess 3153 to aposition that permits engagement of each ball bearing 3180 with ashallow recess 3154. Rotation of cam 3150 may be achieved by applicationof a force (e.g., a torque) to notch 3172 (e.g., via torque surface3173), which drives rotation of prongs 3174 and, in turn, rotation ofengaged grooves 3152. FIG. 3C illustrates a plan view of a bone screwassembly in an undeployed position according to a specific exampleembodiment of the disclosure. As shown, ball bearings 3180 are engagedwith deep recesses 3153. A tool (not pictured) may be inserted intonotches 3172 and rotated clockwise (arrows), displacing bearings 3180radially outwardly. This rotation may continue until ball bearings 3180engage shallow recesses 3154; at which point bearings 3180 come to restin a deployed position (FIG. 3D). If present, recess 3153 may permitscrew assembly 3120 to “lock” into an undeployed position (e.g., due torecess 3153's contour and/or the resiliency of the material of whichscrew assembly 3120 is constructed). If present, recess 3154 may permitscrew assembly 3120 to “lock” into a deployed position (e.g., due torecess 3154's contour and/or the resiliency of the material of whichscrew assembly 3120 is constructed). If desired, bone screw assembly3120 may be removed by unlocking (e.g., counter-rotating) cam 3150 andbacking out (e.g., counter-rotating) bone screw 3130.

FIG. 4 illustrates a perspective view of bone plate assembly 4200according to a specific example embodiment of the disclosure. As shownbone plate assembly 4200 comprises bone plate 4210 and bone screwassembly 4220. Bone plate 4210 comprises body 4211, through holes 4212,mount 4216, and aperture 4217. Each through hole 4212 defines a central,longitudinal axis generally perpendicular to the plane of body 4211(e.g., and/or ±˜5° and/or ±˜20°). Each through hole 4212 comprises innersurface 4214 having recess 4213 and ridge 4215. Recess 4213 may extendalong the entire circumference of inner surface 4214 and/or lie in aplane generally perpendicular to central, longitudinal axis of throughhole 4212. Bone screw assembly 4220 comprises bone screw 4230, threads4232, race 4260, and bone screw pin 4285. Bone screw assembly 4220 isfitted into one of through holes 4212 with each bone screw pin 4285 in adeployed position, engaged in through hole recess 4213. According tosome embodiments, one or more of recesses 4213 may be sized the same asor just slightly larger than the size of bone screw pins 4285. Boneplate assembly 4200 may comprise, in some embodiments, a like number ofbone screw assemblies 4220 and through holes 4212.

A bone screw assembly 5220 may comprise bone screw 5230, deployableprotrusion 5285, and protrusion driver 5260 according to someembodiments (e.g., FIGS. 5A-5D). Bone screw 5230 may comprise body 5231and bone screw head 5240. Bone screw body 5231 may have one or morethreads 5232 spanning threaded portion 5233, which may be configured toadvance and/or fix bone screw 5230 in a hole in a matrix (e.g., bone).For example, threads 5232 may spirally surround the outer longitudinalcircumference of body 5231, tapering to tip 5234. Bone screw body 5230may have central, longitudinal axis 5235.

Bone screw head 5240 may comprise notch 5242, torque surface 5243,through holes 5244, through holes 5245, stowed circumferential recess5247, and deployed circumferential recess 5248. Notch 5242 may beconfigured to rotate about an axis parallel to and/or rotate in a planegenerally perpendicular to longitudinal axis 5235 of bone screw 5230.Each notch 5242 may span the radial thickness of body 5241. Notches 5242may be configured to receive a mated installation tool (e.g., a cylinderwith axially protruding circumferential pins dimensioned to engagenotches 5242 and/or surfaces 5243). Upon application of a force (e.g.,torque) to torque surface 5243, bone screw 5230 may rotate about centrallongitudinal axis 5235 and, optionally, propel tip 5234 into a matrix(e.g., bone). Stowed circumferential recess 5247, and deployedcircumferential recess 5248 may lie in a plane generally perpendicularto longitudinal axis 5235 of bone screw 5230 and/or generally parallelto the rotational plane of notch 5242. Deployed circumferential recess5248 may be positioned closer to tip 5234 and/or more distant from theapex of bone screw 5230 than stowed circumferential recess 5247. Holes5244 may receive bone screw pins 5285 (e.g., from their interior facesas illustrated in FIG. 5A). Each hole 5244 and/or each hole 5245 mayindependently have a longitudinal axis that is perpendicular to center,longitudinal axis 5235 of bone screw 5230. Each hole 5244 mayindependently have a diameter that is uniform along its full length. Insome embodiments, each hole 5244 may independently have a narrowing ator near the end more distal to center, longitudinal axis 5235 of bonescrew 5230. Holes 5244 and 5245 may be distributed at regular intervals,as shown, or irregular intervals around the circumference of bone screwhead 5240. Bone screw 5230 may be a single piece or two or moreconjoined parts according to some embodiments.

Bone screw race 5260 may comprise body 5261, notches 5262, each withsurfaces 5263, cam surface 5264, central aperture 5265, central apertureinner surface 5266, slot 5267, and/or nub 5268. Body 5261 may itselfdefine and/or comprise central aperture 5265 and/or may taper at oneend. In some embodiments, race 5260 may be solid and lack centralaperture 5265. Race 5260 may be generally circular (e.g., annular) witha diameter greater than it's thickness. Each notch 5262 may span theradial thickness of body 5261 and/or only a portion of the longitudinalthickness of body 5261. Two or more notches 5262—may be positioned onthe same face of race 5260 as one another and/or opposite of cam surface5264. Slot 5267 may span both the radial and longitudinal thickness ofbody 5261 (e.g., defining a gap in an otherwise annular structure). Slot5267 may permit (e.g., independently or in cooperation with theresiliency of race 5260 and/or bone screw head 5240) race 5260 to beradially compressed (e.g., temporarily). This may facilitate movement ofrace 5260 between stowed positions and deployed positions and/orinstallation of race 5260 in bone screw 5230. Slot 5267 may be separatefrom (as shown) or contiguous with a notch 5262. Race 5260 may fit(e.g., slidably fit) within a cavity in bone screw head 5240 (e.g., ator near the apex of bone screw 5230). For example, race 5260 may fitwithin bone screw head 5230 such that it may slide (e.g., reversibly)along longitudinal axis 5235 of bone screw 5230. Race 5260 may bepositioned within bone screw head 5240 such that nub 5268 engages stowedcircumferential recess 5247 (stowed position) or deployedcircumferential recess 5248 (deployed position). As shown, race 5260 maybe positioned such that it is flush with bone screw head 5240 (itssurface farthest from tip 5234 is level with the surface of bone screwhead 5240 that is farthest from tip 5234) in a stowed position. Whenmoved to a deployed position, race 5260 is depressed into bone screwhead 5240. Alternatively, race 5260 may be positioned such it is abovebone screw head 5240 in a stowed position. When moved to a deployedposition, race 5260 then becomes flush with bone screw head 5240. Camsurface 5264 may independently contact one or more bone screw pins 5285.

Bone screw pin 5285 may have a generally cylindrical shape and/orcomprise proximal end 5286, ridge 5287, and distal end 5288. Proximalend 5286 may be flat or domed. Distal end 5288 may be flat or domed.Proximal end 5286 may be positioned more proximal to central axis 5235than distal end 5288. Ridge 5267 may engage stop 5249 (e.g., when pin5285 is in a deployed position.

FIGS. 6A-6F illustrate perspective, plan, and section views of bonescrew assembly 6220 with bone screw pins 6285 in a stowed position(FIGS. 6A, 6C, and 6E) and a deployed position (FIGS. 6B, 6D, and 6F).As shown, each bone screw pin 6285 in an undeployed (or stowed) positionmay (a) occupy a hole 6244, (b) engage a deep recess 6253 such that itsouter edge is substantially flush with the outer surface of head 6240,and/or (c) have little or no opportunity for contact with plate 6210(FIGS. 6A, 6C, and 6E). Each bone screw pin 6285 in a deployed positionmay (a) partially occupy a hole 6244, (b) engage a shallow recess 6254such that it protrudes from hole 6244 beyond the outer surface of head6240, and/or (c) has sufficient exposure to contact plate 6210 (FIGS.6B, 6D, and 6F).

In use, each bone screw pin 6285 may be deployed upon application of aforce generally along and/or parallel to central axis 6235 and directedtoward tip 6234. Race 6260 may slide (e.g., snap) from a stowed positionmore distant from tip 6234 to a deployed position closer to tip 6234 inwhich nub 6268 moves from engagement with stowed circumferential recess6247 to engagement with deployed circumferential recess 6248. Suchmovement may slide cam surface 6264 across proximal end 6286 anddisplace (e.g., cam) bone screw pins 6285 radially outwardly from astowed position to a deployed position. A tool (not pictured) may beinserted into notches 6262 and used to drive race 6260 towards tip 6235.This may continue until nub 6268 engages recess 6248; at which pointpins 6285 come to rest in a deployed position (FIG. 6D). If present,recess 6247 may permit screw assembly 6220 to “lock” into an undeployedposition (e.g., due to recess 6247's contour and/or the resiliency ofthe material of which screw assembly 6220 is constructed). If present,recess 6248 may permit screw assembly 6220 to “lock” into a deployedposition (e.g., due to recess 6248's contour and/or the resiliency ofthe material of which screw assembly 6220 is constructed). If desired,bone screw assembly 6220 may be removed by unlocking race 6250 (e.g., byinserting a tool into the center of the race, engaging the tool with anundercut in the center bore of the race, and pulling the race up to theundeployed position) and backing out (e.g., counter-rotating) bone screw6230.

FIG. 7 illustrates a perspective view of bone plate assembly 7300according to a specific example embodiment of the disclosure. As shownbone plate assembly 7300 comprises bone plate 7310 and bone screwassembly 7320. Bone plate 7310 comprises body 7311, through holes 7312,mount 7316, and aperture 7317. Each through hole 7312 defines a central,longitudinal axis generally perpendicular to the plane of body 7311(e.g., and/or ±˜5° and/or ±˜20°). Each through hole 7312 comprises innersurface 7314 having recess 7313 and ridge 7315. Recess 7313 may extendalong the entire circumference of inner surface 7314 and/or lie in aplane generally perpendicular to central, longitudinal axis of throughhole 7312. Bone screw assembly 7320 comprises bone screw 7330, threads7332, race 7360, and bone screw pin 7385. Bone screw assembly 7320 isfitted into one of through holes 7312 with each bone screw pin 7385 in adeployed position, engaged in through hole recess 7313. According tosome embodiments, one or more of recesses 7313 may be sized the same asor just slightly larger than the size of bone screw pins 7385. Boneplate assembly 7300 may comprise, in some embodiments, a like number ofbone screw assemblies 7320 and through holes 7312.

A bone screw assembly 8320 may comprise bone screw 8330, deployableprotrusion 8385, and protrusion driver 8360 according to someembodiments (e.g., FIGS. 8A-8D). Bone screw 8330 may comprise body 8331and bone screw head 8340. Bone screw body 8331 may have one or morethreads 8332 spanning threaded portion 8333, which may be configured toadvance and/or fix bone screw 8330 in a hole in a matrix (e.g., bone).For example, threads 8332 may spirally surround the outer longitudinalcircumference of body 8331, tapering to tip 8334. Bone screw body 8330may have central, longitudinal axis 8335.

Bone screw head 8340 may comprise notch 8342, torque surface 8343,through holes 8344, through holes 8345, stowed circumferential recess8347, and deployed circumferential recess 8348. Notch 8342 may beconfigured to rotate about an axis parallel to and/or rotate in a planegenerally perpendicular to longitudinal axis 8335 of bone screw 8330.Each notch 8342 may span the radial thickness of body 8341. Notches 8342may be configured to receive a mated installation tool (e.g., a cylinderwith axially protruding circumferential pins dimensioned to engagenotches 8342 and/or surfaces 8343). Upon application of a force (e.g.,torque) to torque surface 8343, bone screw 8330 may rotate about centrallongitudinal axis 8335 and, optionally, propel tip 8334 into a matrix(e.g., bone). Stowed circumferential recess 8347, and deployedcircumferential recess 8348 may lie in a plane generally perpendicularto longitudinal axis 8335 of bone screw 8330 and/or generally parallelto the rotational plane of notch 8342. Deployed circumferential recess8348 may be positioned closer to tip 8334 and/or more distant from theapex of bone screw 8330 than stowed circumferential recess 8347. Holes8344 may receive bone screw pins 8385 (e.g., from their interior facesas illustrated in FIG. 8A). Each hole 8344 and/or each hole 8345 mayindependently have a longitudinal axis that is perpendicular to center,longitudinal axis 8335 of bone screw 8330. Each hole 8344 mayindependently have a diameter that is uniform along its full length. Insome embodiments, each hole 8344 may independently have a narrowing ator near the end more distal to center, longitudinal axis 8335 of bonescrew 8330. Holes 8344 and 8345 may be distributed at regular intervals,as shown, or irregular intervals around the circumference of bone screwhead 8340. Bone screw 8330 may be a single piece or two or moreconjoined parts according to some embodiments.

Bone screw race 8360 may comprise body 8361, surface 8363, cam surface8364, central aperture 8365, central aperture inner surface 8366, slot8367, nub 8368, and/or threads 8369 (along inner surface 8366). Body8361 may itself define and/or comprise central aperture 8365 and/or maytaper at one end. Race 8360 may be generally circular (e.g., annular)with a diameter greater than it's thickness. Slot 8367 may span both theradial and longitudinal thickness of body 8361 (e.g., defining a gap inan otherwise annular structure). Slot 8367 may permit (e.g.,independently or in cooperation with the resiliency of race 8360 and/orbone screw head 8340) race 8360 to be radially compressed (e.g.,temporarily). This may facilitate movement of race 5260 between stowedpositions and deployed positions and/or installation of race 8360 inbone screw 8330.

Race 8360 may fit (e.g., slidably fit) within a cavity in bone screwhead 8340 (e.g., at or near the apex of bone screw 8330). For example,race 8360 may fit within bone screw head 8330 such that it may slide(e.g., reversibly) along longitudinal axis 8335 of bone screw 8330. Race8360 may be positioned within bone screw head 8340 such that nub 8368engages stowed circumferential recess 8347 (stowed position) or deployedcircumferential recess 8348 (deployed position). As shown, race 8360 maybe positioned such that it is flush with bone screw head 8340 (itssurface 8363 farthest from tip 8334 is level with the surface of bonescrew head 8340 that is farthest from tip 8334) in a stowed position.When moved to a deployed position, race 8360 is depressed into bonescrew head 8340. Alternatively, race 8360 may be positioned such it isabove bone screw head 8340 in a stowed position. When moved to adeployed position, race 8360 then becomes flush with bone screw head8340. Cam surface 8364 may independently contact one or more bone screwpins 8385.

Bone screw pin 8385 may have a generally cylindrical shape and/orcomprise proximal end 8386, ridge 8387, and distal end 8388. Proximalend 8386 may be flat or domed. Distal end 8388 may be flat or domed.Proximal end 8386 may be positioned more proximal to central axis 8335than distal end 8388. Ridge 8367 may engage stop 8349 (e.g., when pin8385 is in a deployed position.

FIGS. 9A-9F illustrate perspective, plan, and section views of bonescrew assembly 9320 with bone screw pins 9385 in a stowed position(FIGS. 9A, 9C, and 9E) and a deployed position (FIGS. 9B, 9D, and 9F).As shown, each bone screw pin 9385 in an undeployed (or stowed) positionmay (a) occupy a hole 9344, (b) engage a deep recess 9353 such that itsouter edge is substantially flush with the outer surface of head 9340,and/or (c) have little or no opportunity for contact with plate 9310(FIGS. 9A, 9C, and 9E). Each bone screw pin 9385 in a deployed positionmay (a) partially occupy a hole 9344, (b) engage a shallow recess 9354such that it protrudes from hole 9344 beyond the outer surface of head9340, and/or (c) has sufficient exposure to contact plate 9310 (FIGS.9B, 9D, and 9F).

In use, each bone screw pin 9385 may be deployed upon application of aforce generally along and/or parallel to central axis 9335 and directedtoward tip 9334. Race 9360 may slide (e.g., snap) from a stowed positionmore distant from tip 9334 to a deployed position closer to tip 9334 inwhich nub 9368 moves from engagement with stowed circumferential recess9347 to engagement with deployed circumferential recess 9348. Suchmovement may slide cam surface 9364 across proximal end 9386 anddisplace (e.g., cam) bone screw pins 9385 radially outwardly from astowed position to a deployed position. A tool (not pictured) may beinserted into central aperture 8365 such that it engages threads 8369and used to drive race 9360 towards tip 9335. A tool for engagingcentral aperture 8365 may comprise, for example, a threaded tip thatresembles a screw. This may continue until nub 9368 engages recess 9348;at which point pins 9385 come to rest in a deployed position (FIG. 9D).If present, recess 9347 may permit screw assembly 9320 to “lock” into anundeployed position (e.g., due to recess 9347's contour and/or theresiliency of the material of which screw assembly 9320 is constructed).If present, recess 9348 may permit screw assembly 9320 to “lock” into adeployed position (e.g., due to recess 9348's contour and/or theresiliency of the material of which screw assembly 9320 is constructed).If desired, bone screw assembly 9320 may be removed by unlocking race9360 (e.g., pulling it axially away from tip 9334) and backing out(e.g., counter-rotating) bone screw 9330.

FIG. 10A illustrates a perspective view of bone plate assembly 10400according to a specific example embodiment of the disclosure. As shownbone plate assembly 10400 comprises bone plate 10410 and bone screwassembly 10420. Bone plate 10410 comprises body 10411, through holes10412, mount 10416, and aperture 10417 (FIG. 10B). Bone plate assembly10400 may comprise 4 through holes 10412 (FIGS. 10A and 10B) or 6through holes 10412 (FIG. 10C). Each through hole 10412 defines acentral, longitudinal axis generally perpendicular to the plane of body10411 (e.g., and/or ±˜5° and/or ±˜20°). Each through hole 10412comprises inner surface 10414 having recess 10413 and ridge 10415.Recess 10413 may extend along the entire circumference of inner surface10414 and/or lie in a plane generally perpendicular to central,longitudinal axis of through hole 10412. Bone screw assembly 10420comprises bone screw 10430, threads 10432, race 10460, and bone screwpin 10485. Bone screw assembly 10420 is fitted into one of through holes10412 with each bone screw pin 10485 in a deployed position, engaged inthrough hole recess 10413. According to some embodiments, one or more ofrecesses 10413 may be sized the same as or just slightly larger than thesize of bone screw pins 10485. Bone plate assembly 10400 may comprise,in some embodiments, a like number of bone screw assemblies 10420 andthrough holes 10412.

A bone screw assembly 11420 may comprise bone screw 11430, deployableprotrusion 11485, and protrusion driver 11460 according to someembodiments (e.g., FIGS. 11A-11D). Bone screw 11430 may comprise body11431 and bone screw head 11440. Bone screw body 11431 may have one ormore threads 11432 spanning threaded portion 11433, which may beconfigured to advance and/or fix bone screw 11430 in a hole in a matrix(e.g., bone). For example, threads 11432 may spirally surround the outerlongitudinal circumference of body 11431, tapering to tip 11434. Bonescrew body 11430 may have central, longitudinal axis 11435.

Bone screw head 11440 may comprise notch 11442, torque surface 11443,through holes 11444, through holes 11445, stowed circumferential recess11447, and deployed circumferential recess 11448. Notch 11442 may beconfigured to rotate about an axis parallel to and/or rotate in a planegenerally perpendicular to longitudinal axis 11435 of bone screw 11430.Each notch 11442 may be bounded by inner notch wall 11442A and, thus,only partially span the radial thickness of body 11441, in contrast tothrough holes 12444 and 12445, which may span the full radial thicknessof body 11441. Notches 11442 may be configured to receive a matedinstallation tool (e.g., a cylinder with axially protrudingcircumferential pins dimensioned to engage notches 5242 and/or surfaces5243). Upon application of a force (e.g., torque) to torque surface11443, bone screw 11430 may rotate about central longitudinal axis 11435and, optionally, propel tip 11434 into a matrix (e.g., bone). Stowedcircumferential recess 11447, and deployed circumferential recess 11448may lie in a plane generally perpendicular to longitudinal axis 11435 ofbone screw 11430 and/or generally parallel to the rotational plane ofnotch 11442. Deployed circumferential recess 11448 may be positionedcloser to tip 11434 and/or more distant from the apex of bone screw11430 than stowed circumferential recess 11447. Holes 11444 may receivebone screw pins 11485 (e.g., from their interior faces as illustrated inFIG. 11A). Each hole 11444 and/or each hole 11445 may independently havea longitudinal axis that is perpendicular to center, longitudinal axis11435 of bone screw 11430. Each hole 11444 may independently have adiameter that is uniform along its full length. In some embodiments,each hole 11444 may independently have a narrowing at or near the endmore distal to center, longitudinal axis 11435 of bone screw 11430.Holes 11444 and 11445 may be distributed at regular intervals, as shown,or irregular intervals around the circumference of bone screw head11440. Bone screw 11430 may be a single piece or two or more conjoinedparts according to some embodiments.

Bone screw race 11460 may comprise body 11461, notches 11462, each withsurfaces 11463, cam surface 11464, central aperture 11465, centralaperture inner surface 11466, slot 11467, and/or nub 11468. Body 11461may itself define and/or comprise central aperture 11465 and/or maytaper at one end. In some embodiments, race 11460 may be solid and lackcentral aperture 11465. Race 11460 may be generally circular (e.g.,annular) with a diameter greater than it's thickness. Each notch 11462may span the radial thickness of body 11461 and/or only a portion of thelongitudinal thickness of body 11461. Two or more notches 11462—may bepositioned on the same face of race 11460 as one another and/or oppositeof cam surface 11464. Slot 11467 may span both the radial andlongitudinal thickness of body 11461 (e.g., defining a gap in anotherwise annular structure). Slot 11467 may permit (e.g., independentlyor in cooperation with the resiliency of race 11460 and/or bone screwhead 11440) race 11460 to be radially compressed (e.g., temporarily).This may facilitate movement of race 11460 between stowed positions anddeployed positions and/or installation of race 11460 in bone screw11430. Slot 11467 may be contiguous with (as shown) or separate from anotch 11462. Race 11460 may fit (e.g., slidably fit) within a cavity inbone screw head 11440 (e.g., at or near the apex of bone screw 11430).For example, race 11460 may fit within bone screw head 11430 such thatit may slide (e.g., reversibly) along longitudinal axis 11435 of bonescrew 11430. Race 11460 may be positioned within bone screw head 11440such that nub 11468 engages stowed circumferential recess 11447 (stowedposition) or deployed circumferential recess 11448 (deployed position).As shown, race 11460 may be positioned such that it is flush with bonescrew head 11440 (its surface farthest from tip 11434 is level with thesurface of bone screw head 11440 that is farthest from tip 11434) in astowed position. When moved to a deployed position, race 11460 isdepressed into bone screw head 11440. Alternatively, race 11460 may bepositioned such it is above bone screw head 11440 in a stowed position.When moved to a deployed position, race 11460 then becomes flush withbone screw head 11440. Cam surface 11464 may independently contact oneor more bone screw pins 11485.

Bone screw pin 11485 may have a generally cylindrical shape and/orcomprise proximal end 11486, ridge 11487, and distal end 11488. Proximalend 11486 may be flat or domed. Distal end 11488 may be flat or domed.Proximal end 11486 may be positioned more proximal to central axis 11435than distal end 11488. Ridge 11467 may engage stop 11449 (e.g., when pin11485 is in a deployed position.

FIGS. 12A-12F illustrate perspective, plan, and section views of bonescrew assembly 12420 with bone screw pins 12485 in a stowed position(FIGS. 12A, 12C, and 12E) and a deployed position (FIGS. 12B, 12D, and12F). As shown, each bone screw pin 12485 in an undeployed (or stowed)position may (a) occupy a hole 12444, (b) engage a deep recess 12453such that its outer edge is substantially flush with the outer surfaceof head 12440, and/or (c) have little or no opportunity for contact withplate 12410 (FIGS. 12A, 12C, and 12E). Each bone screw pin 12485 in adeployed position may (a) partially occupy a hole 12444, (b) engage ashallow recess 12454 such it that protrudes from hole 12444 beyond theouter surface of head 12440, and/or (c) has sufficient exposure tocontact plate 12410 (FIGS. 12B, 12D, and 12F).

In use, each bone screw pin 12485 may be deployed upon application of aforce generally along and/or parallel to central axis 12435 and directedtoward tip 12434. Race 12460 may slide (e.g., snap) from a stowedposition more distant from tip 12434 to a deployed position closer totip 12434 in which nub 12468 moves from engagement with stowedcircumferential recess 12447 to engagement with deployed circumferentialrecess 12448. Such movement may slide cam surface 12464 across proximalend 12486 and displace (e.g., cam) bone screw pins 12485 radiallyoutwardly from a stowed position to a deployed position. A tool (notpictured) may be inserted into notches 124124 and used to drive race12460 towards tip 12435. This may continue until nub 12468 engagesrecess 12448; at which point pins 12485 come to rest in a deployedposition (FIG. 12D). If present, recess 12447 may permit screw assembly12420 to “lock” into an undeployed position (e.g., due to recess 12447'scontour and/or the resiliency of the material of which screw assembly12420 is constructed). If present, recess 12448 may permit screwassembly 12420 to “lock” into a deployed position (e.g., due to recess12448's contour and/or the resiliency of the material of which screwassembly 12420 is constructed). If desired, bone screw assembly 12420may be removed by unlocking race 12450 (e.g., by inserting a tool intothe center of the race, engaging the tool with an undercut in the centerbore of the race, and pulling the race up to the undeployed position)and backing out (e.g., counter-rotating) bone screw 12430.

As will be understood by those skilled in the art who have the benefitof the instant disclosure, other equivalent or alternative lockingmechanisms for a screw (e.g., a bone screw) and associated devices,systems, and methods can be envisioned without departing from thedescription contained herein. Accordingly, the manner of carrying outthe disclosure as shown and described is to be construed as illustrativeonly.

Persons skilled in the art may make various changes in the shape, size,number, and/or arrangement of parts without departing from the scope ofthe instant disclosure. For example, the position and number of throughholes 12, through hole recesses 13, mounts 16, apertures 17, bone screwassemblies 20, threads 32, notches 42, recesses 44, holes 45, recesses47 m recesses 48, stops 49, grooves 52, recesses 53, recesses 54,notches 62, surfaces 164, nubs 68, threads 69, notches 72, prongs 174,ball bearings 80, and/or pins 85 may be varied. In some embodiments,bone screw assemblies 20 may be interchangeable. Interchangeability mayallow selection of the locking mechanism to be custom adjusted. Inaddition, the size of a device and/or system may be scaled up (e.g., tobe used for adult subjects) or down (e.g., to be used for juvenilesubjects) to suit the needs and/or desires of a practitioner. Eachdisclosed method and method step may be performed in association withany other disclosed method or method step and in any order according tosome embodiments. Where the verb “may” appears, it is intended to conveyan optional and/or permissive condition, but its use is not intended tosuggest any lack of operability unless otherwise indicated. Personsskilled in the art may make various changes in methods of preparing andusing a composition, device, and/or system of the disclosure. Forexample, a system, device, and/or method may be prepared and or used asappropriate for animal and/or human use (e.g., with regard to sanitary,infectivity, safety, toxicity, biometric, and other considerations).

All or a portion of a device and/or system for locking a fastener (e.g.,a bone screw) may be configured and arranged to be disposable,serviceable, interchangeable, and/or replaceable. These equivalents andalternatives along with obvious changes and modifications are intendedto be included within the scope of the present disclosure. Accordingly,the foregoing disclosure is intended to be illustrative, but notlimiting, of the scope of the disclosure as illustrated by the appendedclaims.

What is claimed is:
 1. A lockable bone plate assembly, comprising: abone plate including a through hole having a recess, and a bone screwassembly including a bone screw, a deployable protrusion having a stowedposition at least partially within the bone screw and a deployedposition at least partially protruding from the bone screw, thedeployable protrusion being operable to engage the recess of the boneplate, and a protrusion driver in mechanical communication with thedeployable protrusion and operable to drive the deployable protrusionfrom the stowed position to the deployed position, a contacting surfacebetween the protrusion driver and the deployable protrusion having afirst radial distance in the stowed position and a second radialdistance different from the first radial distance in the deployedposition, wherein the protrusion driver includes a cam, and a profile ofan outer circumference of the cam varies radially in a cross-sectiontaken transverse to a rotational axis of the cam.
 2. A lockable boneplate assembly according to claim 1, wherein the protrusion driver isoperable to move the deployable protrusion radially outwardly from thestowed position to the deployed position.
 3. A lockable bone plateassembly according to claim 1, wherein the protrusion driver has adeployed position corresponding to the deployed position of thedeployable protrusion.
 4. A lockable bone plate assembly according toclaim 3, wherein the protrusion driver is operable to lock in thedeployed position.
 5. A lockable bone plate assembly according to claim3, wherein the bone screw includes a first surface feature, and theprotrusion driver includes a second surface feature operable to engagethe first surface feature and to lock the protrusion driver in itsdeployed position.
 6. A lockable bone plate assembly according to claim1, wherein the bone screw includes a central, longitudinal axis and abone screw head having at least one notch, and each of the bone screwand the bone screw head includes a torque surface operable to receive atorque and translate the torque to rotation of the bone screw about thecentral, longitudinal axis.
 7. A lockable bone plate assembly accordingto claim 1, wherein the bone screw has a central longitudinal axis andincludes: a bone screw body having threads that taper to a tip; and abone screw head fixed to the bone screw body on an end opposite to thetip.
 8. A lockable bone plate assembly, comprising a bone plateincluding a through hole having a recess, and a bone screw assemblyincluding a bone screw, a deployable protrusion having a stowed positionat least partially within the bone screw and a deployed position atleast partially protruding from the bone screw, the deployableprotrusion being operable to engage the recess of the bone plate, and aprotrusion driver in mechanical communication with the deployableprotrusion and operable to drive the deployable protrusion from thestowed position to the deployed position, a contacting surface betweenthe protrusion driver and the deployable protrusion having a firstradial distance in the stowed position and a second radial distancedifferent from the first radial distance in the deployed position,wherein the bone screw has a central longitudinal axis and includes: abone screw body having threads that taper to a tip; and a bone screwhead fixed to the bone screw body on an end opposite to the tip, and thebone screw head includes an annular groove encircling a notch.
 9. Alockable bone plate assembly, the lockable bone plate assemblycomprising: a bone plate comprising at least one through hole, the atleast one through hole having at least one bone plate holecircumferential recess, and a bone screw assembly comprising, (a) a bonescrew, (b) at least one deployable protrusion having a stowed positionsubstantially within the bone screw and a deployed position at leastpartially protruding from the bone screw and engaged with the at leastone bone plate hole circumferential recess, and (c) a protrusion driverin mechanical communication with the deployable protrusion and operableto drive the deployable protrusion from the stowed position to thedeployed position, wherein the vertical position of the bone screwassembly relative to the bone plate is locked when the deployableprotrusion is in the deployed position, wherein the bone screw has acentral longitudinal axis and comprises: a bone screw body comprisingthreads that taper to a tip; and a bone screw head fixed to the bonescrew body on the end opposite the tip, the bone screw head comprisingat least one notch, the bone screw head further comprises an annulargroove encircling the at least one notch, and the bone screw assemblyfurther comprises: an annular bone screw cam positioned in the annulargroove and comprising on its outer circumferential surface at least oneaxial groove, at least one axial deep recess, and at least one axialshallow recess between the axial groove and the axial deep recess; andan annular bone screw cap comprising a first surface comprising at leastone bone screw cap notch and second surface opposing the first facingthe annular bone screw cam and comprising at least one prong, whereinthe at least one deep recess is configured to engage the deployableprotrusion in its stowed position, the at least one shallow recess isconfigured to engage the deployable protrusion in its deployed position,and the at least one axial groove is in mechanical communication withthe at least one prong to produce tandem rotation of the annular bonescrew cam and annular bone screw cap about the central, longitudinalaxis.
 10. A lockable bone plate assembly according to claim 9, whereinthe annular bone screw cap further comprises at least onecircumferential notch comprising a torque surface, the torque surfaceconfigured to receive a torque and translate the torque to rotation ofthe bone screw cap about the central, longitudinal axis.
 11. A lockablebone plate assembly, comprising a bone plate including a through holehaving a recess, and a bone screw assembly including a bone screw, adeployable protrusion having a stowed position at least partially withinthe bone screw and a deployed position at least partially protrudingfrom the bone screw, the deployable protrusion being operable to engagethe recess of the bone plate, and a protrusion driver in mechanicalcommunication with the deployable protrusion and operable to drive thedeployable protrusion from the stowed position to the deployed position,a contacting surface between the protrusion driver and the deployableprotrusion having a first radial distance in the stowed position and asecond radial distance different from the first radial distance in thedeployed position, wherein the bone screw has a central longitudinalaxis and includes: a bone screw body having threads that taper to a tip;and a bone screw head fixed to the bone screw body on an end opposite tothe tip, the bone screw head includes a cavity having a cavity innersurface, and the cavity inner surface includes a stowed recess and adeployed recess, the deployed recess being closer to the tip than thestowed recess.
 12. A lockable bone plate assembly, the lockable boneplate assembly comprising: a bone plate comprising at least one throughhole, the at least one through hole having at least one bone plate holecircumferential recess, and a bone screw assembly comprising, (a) a bonescrew, (b) at least one deployable protrusion having a stowed positionsubstantially within the bone screw and a deployed position at leastpartially protruding from the bone screw and engaged with the at leastone bone plate hole circumferential recess, and (c) a protrusion driverin mechanical communication with the deployable protrusion and operableto drive the deployable protrusion from the stowed position to thedeployed position, wherein the vertical position of the bone screwassembly relative to the bone plate is locked when the deployableprotrusion is in the deployed position, wherein the bone screw has acentral longitudinal axis and comprises: a bone screw body comprisingthreads that taper to a tip; and a bone screw head fixed to the bonescrew body on the end opposite the tip, the bone screw head comprisingat least one notch, and the bone screw assembly further comprises: anannular bone screw race in the central cavity having a stowed positionand a deployed position, the annular bone screw race comprising a firstend, an outer circumferential surface comprising at least onecircumferential nub and at least one cam surface, and a second endopposite the first end, wherein the nub engages the stowedcircumferential recess in the stowed position of the race and the nubengages the deployed circumferential recess in the deployed position ofthe race.
 13. A lockable bone plate assembly according to claim 12,wherein the deployable protrusion comprises a bone screw pin having agenerally cylindrical shape and comprising a proximal end in mechanicalcommunication with the at least one cam surface of the annular bonescrew race and a distal end engageable with the at least one bone platehole circumferential recess.
 14. A lockable bone plate assemblyaccording to claim 13, wherein the annular bone screw race furthercomprises a slot spanning its radial and longitudinal thickness.
 15. Alockable bone plate assembly according to claim 14, wherein the annularbone screw race comprises a central aperture comprising a centralaperture surface, the central aperture surface comprising threads.
 16. Alockable bone plate assembly according to claim 14, wherein the firstend of the cam comprise at least one cam notch and the slot is distinctfrom each at least one cam notch.
 17. A lockable bone plate assemblyaccording to claim 14, wherein the slot is contiguous with at least onecam notch.
 18. A method of vertebral fixation, comprising: contacting atleast a portion of a spine of a subject with a lockable bone plateassembly, the lockable bone plate assembly including: a bone plateincluding a through hole having a recess, and a bone screw assemblyincluding a bone screw, a deployable protrusion having a stowed positionat least partially within the bone screw and a deployed position atleast partially protruding from the bone screw, the deployableprotrusion being operable to engage the recess of the bone plate, and aprotrusion driver in mechanical communication with the deployableprotrusion and operable to drive the deployable protrusion from thestowed position to the deployed position, a contacting surface betweenthe protrusion driver and the deployable protrusion having a firstradial distance in the stowed position and a second radial distancedifferent from the first radial distance in the deployed position,wherein the protrusion driver includes a cam, and a profile of an outercircumference of the cam varies radially in a cross-section takentransverse to a rotational axis of the cam.
 19. A method of vertebralfixation according to claim 18, wherein the at least a portion of thespine of the subject includes at least a portion of the subject'scervical spine.
 20. A bone screw assembly, comprising: a bone screw; adeployable protrusion having a stowed position at least partially withinthe bone screw and a deployed position at least partially protrudingfrom the bone screw; and a protrusion driver in mechanical communicationwith the deployable protrusion and operable to drive the deployableprotrusion from the stowed position to the deployed position, acontacting surface between the protrusion driver and the deployableprotrusion having a first radial distance in the stowed position and asecond radial distance different from the first radial distance in thedeployed position, wherein the protrusion driver includes a cam, and aprofile of an outer circumference of the cam varies radially in across-section taken transverse to a rotational axis of the cam.